Since a transparent display apparatus itself contains a certain degree of light transmission, in addition to the original display function, the background behind the screen thus can be revealed. Such that, a transparent display apparatus can be applied to large-scale commercial demonstration and decoration of glass curtain walls, vehicle windows and shop windows. In terms of some design and performance aspects, the transparent display apparatus can show functions that many existing display technologies are difficult to achieve, hence it can be expected that the transparent display apparatus will replace parts of the existing display apparatuses in the future, and can be extensively applied to consumer electronic products, such as smart phones, notebook computers and portable electronic components.
An organic light emitting diode having advantages of simple processes, light, thin, flexible, colorful and a transparent self-luminous layer, has gradually become the main light source for producing the transparent display apparatus. In order to balance the injection carriers, transparent material of indium tin oxide (InSnO) with high work function is adopted by traditional organic light emitting diodes serving as the bottom anode electrodes. In addition, transparent or translucent material, mainly composed of InSnO, may be used to replacing the traditional metal layer to form a cathode electrode for purpose of enhancing its optical transmission property.
However, the cathode electrode mainly composed of transparent InSnO is difficult to be combined with the organic light emitting layer, such that the mass production technologies are still unable to be established. Moreover, traditional transparent display apparatus can simultaneously show images on both front side and back side. But this may bother the users who attach importance to privacy and don't want to show the contents displayed from the back side of the display apparatus.
Therefore, it is necessary to provide a transparent display apparatus with simple process, performing the functions of displaying images and revealing the background, as well as simultaneously taking the privacy of users into account.